World J Surg (2009) 33:412–416 DOI 10.1007/s00268-008-9894-0
A Novel Nomenclature to Classify Parathyroid Adenomas Nancy D. Perrier Æ Beth Edeiken Æ Rodolfo Nunez Æ Isis Gayed Æ Camilo Jimenez Æ Naifa Busaidy Æ Elena Potylchansky Æ Spencer Kee Æ Thinh Vu
Published online: 16 January 2009 Ó Socie´te´ Internationale de Chirurgie 2009
Abstract Background A uniform and reliable description of the exact locations of adenomatous parathyroid glands is necessary for accurate communications between surgeons and other specialists. We developed a nomenclature that provides a precise means of communicating the most frequently encountered parathyroid adenoma locations. Methods This classification scheme is based on the anatomic detail provided by imaging and can be used in radiology reports, operative records, and pathology reports. It is based on quadrants and anterior-posterior depth relative to the course of the recurrent laryngeal nerve and the thyroid parenchyma. The system uses the letters A-G to describe exact gland locations. Results A type A parathyroid gland is a gland that originates from a superior pedicle, lateral to the recurrent laryngeal nerve compressed within the capsule of the thyroid parenchyma. A type B gland is a superior gland that has fallen posteriorly into the tracheoesophageal groove and is in the same cross-sectional plane as the superior portion of the thyroid parenchyma. A type C gland is a gland that has fallen posteriorly into the tracheoesophageal groove and on a cross-sectional view lies at the level of or below the inferior pole of the thyroid gland. A type D gland lies in the midregion of the posterior surface of the thyroid parenchyma, near the junction of the recurrent laryngeal nerve and the inferior thyroid artery or middle thyroidal vein; because of this location, dissection is difficult. A type
N. D. Perrier (&) B. Edeiken R. Nunez I. Gayed C. Jimenez N. Busaidy E. Potylchansky S. Kee T. Vu Department of Surgical Oncology, Unit 444, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA e-mail:
[email protected]
123
E gland is an inferior gland close to the inferior pole of the thyroid parenchyma, lying in the lateral plane with the thyroid parenchyma and anterior half of the trachea. A type F gland is an inferior gland that has descended (fallen) into the thyrothymic ligament or superior thymus; it may appear to be ‘‘ectopic’’ or within the superior mediastinum. An anterior-posterior view shows the type F gland to be anterior to the trachea. A type G gland is a rare, truly intrathyroidal parathyroid gland. Conclusions A reproducible nomenclature can provide a means of consistent communication about parathyroid adenoma location. If uniformly adopted, it has the potential to reliably communicate exact gland location without lengthy descriptions. This system may be beneficial for surgical planning as well as operative and pathology reporting.
Introduction Currently, there is no consistent means of describing parathyroid adenoma locations. Consistent descriptions of parathyroid adenoma locations are important for many reasons [1, 2]. A concise, reliable means of communicating the exact location of enlarged parathyroid glands can facilitate surgical planning, including determining incision placement for minimally invasive procedures, patient positioning, the magnitude of anesthesia needed, the scope of the operation, and the extent of nursing care. For example, precise information about expected adenoma location allows for better planning by the anesthesiologist, who can determine the type of anesthesia needed based on operative complexity, depth of dissection, and projected duration of the procedure. Knowledge of adenoma location
World J Surg (2009) 33:412–416
also helps the operating room. Common descriptors of adenoma location are also helpful in communications between physicians, such as when reviewing the report of an operation performed by another surgeon, particularly if reoperation is being planned, and when documenting the exact location of an excised gland [3]. Furthermore, a common nomenclature facilitates communications between institutions, such as in registering patients for clinical trials and reporting results in the medical literature [4, 5]. Such reports are not currently consistent. For example, some authors refer to glands in the thyrothymic ligament or tracheoesophageal groove as ectopic, while others consider these usual and expected locations [6]. To facilitate multidisciplinary communication, we sought to develop a nomenclature that provides a precise means of communicating parathyroid adenoma locations.
Methods and results In February 2006 we created a nomenclature to describe the most common positions of parathyroid adenomas. The system was designed to be user friendly and easy to remember. The alphabet (A–G) was used because of its simplicity. The nomenclature we developed is based on detailed information provided by either four-dimensional computed tomography, sestamibi scanning, single photon emission computed tomography, or ultrasonography supplemented by intraoperative findings. In an effort to make the system easy to remember, we provided a description of each location that repeatedly uses the letter assigned to that location. The nomenclature emphasizes the anterior-posterior location of enlarged parathyroid glands in reference to the thyroid parenchyma, trachea, and esophagus. The locations are also categorized according to the glands’ embryologic origins (superior or inferior) [7]. Embryologically superior parathyroid glands are usually on a vascular pedicle that is lateral and posterior to the recurrent laryngeal nerve [8]. When adenomatous, these glands may fall posterior to the thyroid tissue or in the tracheoesophageal groove. Glands that are embryologically derived from the inferior pedicle are classified as E or F glands; the pedicles of these glands are medial and slightly more anterior to the recurrent laryngeal nerve. When such glands are enlarged, they may stay in situ or fall anteriorly, along the side of the trachea. D glands are those intimately attached to the mid-posterior surface of the thyroid parenchyma in proximity to the expected location of the recurrent laryngeal nerve. Over the ensuing 2 years, we have fine-tuned the descriptions and have added modifiers to describe unusual and unexpected locations of enlarged parathyroid glands (e.g., a ‘‘?’’ was added for a subgroup of B glands to signify that they are high, i.e., undescended, glands). With
413
this system, there is no truly ectopic gland location. The ‘‘?’’ sign can be used to designate ‘‘high’’ glands that have not descended and the ‘‘-‘‘ sign to designate glands that have fallen more inferiorly than usual. The classification scheme, illustrated in Figs. 1, 2, 3, is as follows: Type A: A type A gland is adherent to the posterior thyroid parenchyma. This gland is in the accepted, expected location of a normal gland. It is almost attached, almost intracapsular. Type B: A type B gland is back behind the thyroid parenchyma. The surgeon should be careful not to miss it. It is exophytic to the thyroid parenchyma and lies in the tracheoesophageal groove (burrow). An undescended gland high in the neck near the carotid bifurcation or mandible is classified as a type B ? gland. Type C: A type C gland is commonly missed; it could be mistaken for the esophagus when palpated. It is caudal to the thyroid parenchyma, in the tracheoesophageal groove. It is more inferior than a type B gland on lateral views. Type C glands are at the level of the inferior pole of the thyroid or inferior to the inferior pole of the thyroid (closer to the clavicle). Figures 4 and 5 show examples of type C glands. Type D: Dissection of a type D gland may be difficult because the gland is dangerously close to the recurrent laryngeal nerve. In these cases, preoperative images do not enable specific determination of origin because of the proximity of a type D gland to important structures; do not let an intern do the resection! Type E: A type E gland is extra easy to resect. It is the most externally located gland because it is not deep in
Fig. 1 Illustration depicting the one dimensional position of glands using the nomenclature system
123
414
Fig. 2 A unidimensional view of gland location. B and C glands are posteriorly located in the tracheoesophageal groove. E and F glands are anterior, near the trachea. A, B, and C glands are posterior, lateral to the recurrent laryngeal nerve; D glands are immediately near the recurrent laryngeal nerve; and E and F glands are anterior, medial to the recurrent laryngeal nerve
World J Surg (2009) 33:412–416
Fig. 4 Preoperative computed tomography scan (CT scan) showing a type C gland that has fallen posteriorly into the tracheoesophageal groove. The radiology report can reflect the exact position by merely stating: ‘‘Left type C gland’’
Fig. 3 With medial rotation and traction of the thyroid parenchyma, the parathyroid glands can usually be found in classic quadrants. Type A glands are close to the thyroid parenchyma; B glands are in the tracheoesophageal groove along the thyroid tissue; C glands are in the tracheoesophageal groove inferior to the thyroid tissue; D glands are immediately adjacent to the recurrent laryngeal nerve; E and F glands are anterior and medial to the course of the nerve; and G glands are in the thyroid parenchyma
the neck. Early on, its ease of resection gives the endocrine surgeon extra confidence. Type F: A type F gland has fallen into the thyrothymic ligament. Frequently, it is referred to as ‘‘ectopic.’’ Resection can be fun because a type F gland can usually be retrieved with delivery of the superior portion of the thymus. For the inexperienced surgeon, however, resection can be frightening because of the delivery from the mediastinum via the neck. Figure 6 shows an example of a type F gland. Type G: A type G gland got caught in thyroid tissue. It is gated into the thyroid parenchyma and is gauche, i.e.,
123
Fig. 5 A right type C gland shown on an operating room specimen template
awkward and unusual. A true intrathyroidal gland is rare—gee!
Discussion Accurate preoperative determination of the location of a suspected parathyroid adenoma can direct the surgical
World J Surg (2009) 33:412–416
Fig. 6 A right type F gland within the thymus shown on an operating room specimen template
approach, minimizing dissection and maximizing efficiency during parathyroidectomy. Knowledge of the precise location of an enlarged parathyroid gland and its relationship to surrounding structures is essential, especially for minimally invasive parathyroidectomy and reoperation for persistent or recurrent disease. Without a common terminology to describe the locations of parathyroid gland locations, communication may break down. For example, a preoperative imaging report may describe an ‘‘inferior’’ adenoma because the gland appears to be located near the inferior pole of the thyroid. Importantly, the information that the gland is posteriorly located in the tracheoesophageal groove on oblique views may be omitted. In the operative report, the surgeon may document that a ‘‘superior’’ gland was resected from the tracheoesophageal groove via the lateral or ‘‘back door’’ approach. If a reoperation is necessary, a future surgeon reading these seemingly discordant radiology and operative reports would be confused. To prevent such miscommunications, we developed a classification scheme for the common locations of adenomatous parathyroid glands. We have found that this system greatly improves communication between radiologists and surgeons and aids in preoperative, intraoperative, and postoperative documentation of gland location because the classification is clinically derived. This nomenclature provides a basic terminology for imaging reports and has been expanded and incorporated into our nursing, anesthesia, operative, and pathology reports. We have found that this system
415
greatly improves communication, removes ambiguity, and makes unnecessary lengthy descriptions of parathyroid gland locations. A clinically useful classification scheme must encompass the attributes of a parathyroid gland’s pedicle and the surrounding structures. Our proposed system is based on the premise that superior glands have a pedicle that originates lateral and posterior to the recurrent laryngeal nerve and that inferior glands have a pedicle that originates medial and anterior to this nerve. The system is also based on gravity patterns—superior glands usually fall posteriorly in the tracheoesophageal groove, and inferior glands fall anteriorly in the plane of the trachea. The classification scheme is useful in numerous ways. Direct, precise, consistent terminology eliminates the need for lengthy descriptions in radiology reports. Such nomenclature also alerts operating room staff to the expected complexity and length of a case and the possible need for special equipment such as nerve monitoring devices or instruments for thymectomy. The system provides a concise means of informing the anesthesiologist about the anticipated location of dissection, which may be important for patient positioning. For example, hyperextension may be necessary for a posteriorly located type C gland lying deep in the tracheoesophageal groove. If the patient’s body habitus prevents hyperextension and a deep dissection is anticipated, general anesthesia may be necessary. An anteriorly placed type E gland in the neck of a thin woman would be easily removable via a small incision under attended local anesthesia. In interpreting prior operative records, a nomenclature would greatly enhance understanding which glands were actually removed or partially resected. In cases of persistent hyperparathyroidism, this could be important in directing further treatment. Further research using this nomenclature to preoperatively identify parathyroid gland locations may be beneficial.
Conclusions Our classification system for parathyroid adenomas provides a means of precisely describing the locations of the glands. This removes ambiguity and may improve communication between specialties. Acknowledgment We acknowledge the support of our generous donors, including grateful patients and the Faith Foundation.
References 1. Hamidi S, Hedayat A, Esfahanian F et al (2007) Distribution of solitary parathyroid adenoma over the parathyroid glands and its surgical management. J Coll Physicians Surg Pak 17:619–621
123
416 2. Debruyne F, Ostyn F, Delaere P (1997) Distribution of the solitary adenoma over the parathyroid glands. J Laryngol Otol 111:459– 460 3. Thompson GB, Grant CS, Perrier ND et al (1999) Reoperative parathyroid surgery in the era of sestamibi scanning and intraoperative parathyroid hormone monitoring. Arch Surg 134:699–704 discussion 704-695 4. Harris GJ (1999) Orbital vascular malformations: a consensus statement on terminology and its clinical implications. Orbital Society. Am J Ophthalmol 127:453–455
123
World J Surg (2009) 33:412–416 5. Spetzler RF, Detwiler PW, Riina HA et al (2002) Modified classification of spinal cord vascular lesions. J Neurosurg 96:145– 156 6. Erbil Y, Barbaros U, Tukenmez M et al (2008) Impact of adenoma weight and ectopic location of parathyroid adenoma on localization study results. World J Surg 32:566–571 7. Akerstrom G, Malmaeus J, Bergstrom R (1984) Surgical anatomy of human parathyroid glands. Surgery 95:14–21 8. Wang C (1976) The anatomic basis of parathyroid surgery. Ann Surg 183:271–275
